based on my experiances of running a fairy-monotype team in local university tournaments, I feel I've reached a consensus on who the most viable fairies are in higher-tiers of play:
Uber:
Arceus-Fairy
Xerneas (power herb+geomancy)
Mega Latias (would be high-OU if not for multi-scale/recover)
Creme of the Crop:
Slurpuff (
http://www.smogon.com/forums/threads/slurpuff.3490208/page-2#post-4999160)
Klefki (excellent typing, priority sub+dual screens with light clay for max safety and team help, and swagger+sub+twave+foul play to grief-stall harder than gliscor)
Azumarill (huge power bellyjet)
Mega Mawile (excellent typing, unparralleled attack, sizable defenses, access to basically the strongest sucker punch in the game)
Togekiss (Paraflinch with all new resistances and immunities forces more switch outs ripe for the twaveing, and access to fire blast/nasty plot/dazzling gleam just stacks another layer of coverage for those pesky steels and dragons)
Sylveon OR
Florges (although sylveon is basically weaker stats-wise on all fronts in comparison to Florges, its higher HP allows it to serve as a better wall in general with a bold nature, in comparison to Florges' defined niche of sp. def, given her access only to light screen and sp.atk lowering status moves. however, in VGC doubles Florges shows her true capability, being an enormous asset as a buff to all grass types in a sunny day/chlorophyll team with moves such as aromatheropy, light screen, and grassy terrain, while boasting the flower veil ability to make curseasaur a total monster. sylveon's baton pass capabilities and access to yawn/substitute/pixilate hyper voice make it the better, if not best, fairy cleric)
Gardevoir AND M-Gardevoir (an assault vest Gardy is just way too good as a reliable offensive tank, sporting a myriad of attack options buffed by a wonderful 125 base sp. atk, making it less bulky than Goodra but hitting harder. especially with dual-stab and access to STAB Psyshock to take out the likes of Jellicent and Tentacruel. while M-Gardy does get a small sp. def, it's colors really show with utility with her access to a calm mind to buff its sp. atk and sp. def to levels assault vest Gardy can't dream of, but having to sacrifice a turn on switch to make the best out of its options, which is hindered by its above-average but not stellar speed. access to sub+willowisp will really challenge some of its larger threats though, and gives it and its team the ability a passive defense boost from that particular opponent. STAB Pixilate Hyper Voice will make gliscor and other sub users cry, and running focus blast on the side will make short work of most steel types. not as reliable on switch, but M-Gardevoir is in no ways anything less than OU capable)
Honorable mentions:
Carbink (stealth rock dual screens, 5 resistances, 1 immunity, decent set up with light clay)
Whimsicott (faster prankster user with a few different tricks in her arsenal such as priority cotton guard, stun spore, etc, but with typing nowhere near as strong as klefki)
Clefable (great mon all-around, with good options, excellent usability as a cleric, and stored power sweeping like no other after some Calm Minds. good, but outclassed)